Conventionally, balloons, airships, and the like, have been known as buoyant aerial vehicles. Each of the buoyant aerial vehicles floats by receiving buoyancy force due to the specific gravity difference between external air and gas filled in the balloon, and thereby, performs flight.
Further, in recent years, for the purpose of carrying a load and performing aerial photography, the development of an unmanned aerial vehicle (a so-called drone) has been conducted. For example, Japanese Patent Laid-Open No. 2014-227016 proposes an invention relating to a remote-control unmanned aerial vehicle provided with a propeller which generates lifting force by rotating, a drive source which rotates the propeller, and control means which controls the drive source (Patent Literature 1).